There are various ways in which power can be supplied to an electrical load operated at or near the potential of a high voltage transmission line. For example, a battery alone might be used, but the battery charge can eventually be depleted to the point where the battery would have to replaced or recharged. Also, power might be supplied from a power supply operated at or near electrical ground potential but, since the power must be delivered to a load operating at or near the potential of the transmission line, expensive means for insulating the load from electrical ground potential is required. Further, the required apparatus can be relatively complex and the lack of electrical decoupling can be disadvantageous.
Alternately, apparatus can be adapted to derive power from the magnetic field surrounding a high voltage transmission line. However, such apparatus would have to be capable of handling current ranging from 0 amps to the maximum currents carried by the transmission line, the latter of which might exceed 2,000 amps in a typical high voltage power system. For such apparatus, no power could be derived in the absence of some minimum current flow in the transmission line, and such minimum current flow might not always be maintained.
U.S. Pat. No. 3,259,762 issued to J. E. Skuderna on July 5, 1966, relates to devices for supplying low voltage power to auxiliary equipment associated with high voltage transmission lines. However, the equipment described is maintained at or near ground potential.
An object of the present invention is to provide a new and improved power supply for supplying power to an electrical load operated at or near the potential of a high voltage transmission line.
A further object of the present invention is to provide apparatus as described which is not overly complex and which does not require costly means to insulate the load from electrical ground by reason of interconnection with the power supply.